1. Field of the Invention
The present invention relates generally to an apparatus for coating a plurality of articles in batches. In particular, the invention relates to an apparatus for applying a biocompatible layer on articles adapted to come into contact with blood or body tissue, e.g. a coagulation-preventing substance so as to render the articles non-thrombogenic.
The invention also relates to a process for coating a plurality of articles in batches, in particular for applying a biocompatible layer on articles adapted to come into contact with blood or body tissue, e.g. a coagulation-preventing substance so as to render the articles non-thrombogenic.
2. Description of Related Art
It is well known that when blood comes into contact with other materials than the fresh natural wall of the blood vessel, for example in surgery with medical instruments such as scalpels, activation of certain circulating cells and enzyme systems takes place resulting in blood coagulation. Release of blood coagels or thrombi in the blood flow could lead to thrombosis, a major cause of death in the industrialised world. Coating the surfaces of solid substrates such as medical instruments with certain polysaccharides such as heparin makes these surfaces non-thrombogenic. EP 0 086 186 B1 and EP 0 495 820 B1 describe generally methods of how to bind polysaccharides to articles in order to make the surfaces of the substrates non-thrombogenic.
Furthermore, it is known to batchwise apply a coagulation-preventing coating on endovascular stents, adapted to be implanted e.g. in coronary artery, by placing the stents in a plurality of cavities interconnected serially by a passageway through which a solution containing the substance to be applied onto the stents is supplied sequentially to the cavities and to the stents placed therein. However, such an arrangement of the cavities and the serial flow passage of the solution therethrough may give rise to cavitation problem which may affect the quality and the uniformity of the coating applied to the articles. Also, the coating capacity of such a setup is limited.
It is an object of the invention to provide an apparatus, which eliminates said drawbacks of the prior art. To this end the apparatus of the present invention comprises an article-carrying plate, said article-carrying plate having a top side and a bottom side, a plurality of wells being formed in said top side for receiving therein a respective article to be coated, each of said wells communicating, via a respective orifice, with a space below said bottom side, said orifices having each a cross-sectional flow area that is smaller than the cross-sectional area of each well; a base plate having an upper surface defining with said bottom side of said article-carrying plate a distribution chamber for receiving and evenly distributing to said orifices a solution containing the coating substance to be applied to said articles, said base plate having an inlet for supplying said solution to said chamber; and a top plate covering said top side of the article-carrying plate and defining therewith a collection chamber for receiving used solution having been flown through said orifices and wells, said top plate having an outlet for discharging said used solution.
In order to multiply the coating capacity of the apparatus a plurality of said article-carrying plates are stacked upon one another.
A further object of the invention is to provide a process for coating a plurality of articles in batches, in particular for applying a biocompatible layer on articles adapted to come into contact with blood or body tissue, said process comprising the steps of: loading at least one article-carrying plate, having a plurality of article-receiving wells, with articles to be coated; supplying a solution containing the substance to be applied to the articles to a distribution chamber upstream of and communicating with said wells of the article-carrying plate; feeding said solution in parallel vertical flows through said wells to apply a coating of said substance on the articles; and removing the articles from the wells of said article-carrying plate after completion of the coating of said articles. Preferably, to increase the coating capacity the process comprises the step of feeding said solution in parallel vertical flows through the wells of a plurality of said article-carrying plates stacked one upon the other.
Other features and particulars of the apparatus and process of the present invention will be clear from the following description and claims together with the accompanying drawings.